The invention relates to a hose or tubular guide catheter to accommodate and guide a balloon catheter for dilatation of coronary arteries of the heart.
From a printed source due to the firm of Schneider Medintag, Zurich, "Guide catheter with atraumatic tip," "Soft Touch" type, a hose or guide catheter of the kind in question is known whose end has an annular edge extending substantially axial to the axis of the catheter. In the immediate region of its end, the catheter has a more or less curved form, to facilitate insertion of the end from the aorta into the opening of a coronary artery, or at least render it possible. The guide catheter is moved manually so that its tip will enter a coronary artery and remain there, whereafter a guide wire is passed through the guide catheter into the coronary artery, and then a balloon catheter is introduced over the guide wire and through the guide catheter until the balloon arrives in the region of a constriction of the coronary artery, where the balloon, limited in diameter, is inflated and the constricted place in the coronary artery is thereby dilated and enlarged.
The diameter of the guide catheter is relatively large so that, with adequate wall thickness, a balloon catheter will pass through. This comparatively large diameter of the guide catheter leads in many cases to its tightly closing the entrance opening of the coronary artery, so that the blood supply of the coronary artery is blocked. The myocardium is thereby rendered ischemic with a risk of mortification.
To avoid this disadvantage, the said company print also mentions a guide catheter having lateral holes at some distance from its tip, through which blood is to enter the guide catheter from the aorta and pass on into the coronary artery. If these lateral openings are too close to the anterior edge of the guide catheter, there is danger that the openings will be located in the region of the coronary artery and thus be closed off by its walls, so that they cannot serve their purpose. If the lateral holes are more distant from the anterior edge of the tip of the guide catheter, blood can indeed flow in, but then there is the disadvantage that contrast medium to be injected into the coronary artery through the guide catheter for X-ray visualization of the artery will leak out of the lateral holes, be lost for purposes of visualizing the coronary artery, and impede or at least impair the X-ray image by entering the aorta. Besides, there is the disadvantage that the lateral holes tend to be clogged by blood clots.